Here you can find your MAC Address, listed as either the "Wireless ID" or "Ethernet ID" (depending on the connection you are using).

Alternative method for locating the wireless MAC address:

The Apple TV Ethernet (wired) and Wireless network MAC addresses can be found on the UPC label on the Apple TV box as "Ethernet ID" and "Wireless ID." (This is also the same label that contains the serial number.)

Open the Chromecast app on your computer. If you have set up your Chromecast recently, you'll find a shortcut to the app on your desktop. Otherwise, Windows users should check the Start Menu; Mac users should check Applications

Click Settings.

Find the MAC address at the bottom of the window. The system's MAC address is located at the bottom-left corner of the Settings menu.